A few thoughts from John Fleck, a writer of journalism and other things, living in New Mexico

Menu

Some good news today on climate change: less drought than we thought

A new paper in today’s Nature by Justin Sheffield and colleagues suggests we’ve been using simplistic calculations that have overestimated the increase in drought globally over the last 60 years in response to greenhouse warming. Scientists typically use the Palmer Drought Severity Index, a bit a statistical black box that bases its drought estimate on a formula that combines precip and temperature data with normals for the geographical spot in question. Using PDSI, people have calculated increasing global drought as a result of global warming.

More realistic calculations, based on the underlying physical principles8 that take into account changes in available energy, humidity and wind speed, suggest that there has been little change in drought over the past 60 years.

The findings imply that there is no necessary correlation between temperature changes and long-term drought variations, which should warn us against using any simplifications regarding their relationship.

4 Comments

Another new paper, from Marty Hoerling and several NOAA colleagues, similarly finds that PDSI seriously exaggerates the effect of temperature on drought conditions (soil water balance). They focused on future time scales (projections through 2100) and the U.S. Great Plains.